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Secondary fan switch getting hot

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Old 03-09-2010, 05:30 PM
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Secondary fan switch getting hot

I have a toggle switch hooked up to my secondary fan and i've noticed that its getting warm, sometimes hot to touch. its a 3 wire toggle switch but i have the fan ground wire hooked up in the engine bay. So i only have the hot fan wire and the source wire from the fuse box. I also found out that if i hook the hot on one side of the fuse it will blow it but it wont on the battery side of the fuse. Its a 15 amp fuse and the fan is supposed to draw only 12 amps. I used 14G wire so i thought it would be fine. Any help would be appreciated guys.. thanks
Old 03-10-2010, 08:31 AM
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Switch To The Cool Side

That’s because it’s not going to a relay.

Rewire the setup so it turns on the fan relay, not the fan directly.


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Last edited by NINÅ; 03-10-2010 at 12:31 PM.
Old 03-10-2010, 11:08 AM
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Re: Switch To The Cool Side

Why would a relay matter? It still has to get power from somewhere and the switch is a 20amp
Old 03-10-2010, 12:32 PM
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Car: LOWERED ♦ CRIMSON METALFLAKE
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Switch To The Cool Side

Why would a relay matter?
The relay matters because instead of 20+ amps flowing thru the switch, only a fraction of 1 amp will flow thru the switch.

switch is a 20amp
The fan draws more than 20 amps.


Happy Racing!

How bout those too scared to drive without headlights in the daytime and the ones that need headlights for a little rain

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Old 03-10-2010, 12:38 PM
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Re: Secondary fan switch getting hot

All you should work with is the fan switch's single green wire(ground wire)... no hot wires and no relays, as those are already connected. So if you're working with the hot wire, then, in effect, it's probably like having connected the power twice, thereby overloading the circuit.

Near the fan switch, splice a wire into the switch's single green wire; run the new wire into the car and connect it to one side of a two-prong toggle switch; wire the other prong to the metal dash frame... done. Flipping the switch completes the ground, turning on the fan.

It's that simple--really.

Last edited by LAFireboyd; 03-10-2010 at 12:49 PM. Reason: clarity
Old 03-10-2010, 12:51 PM
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Re: Secondary fan switch getting hot

toggle switches are suppose to trigger a relay, not supply the power an accessory requires to function...
Old 03-11-2010, 12:44 PM
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Re: Secondary fan switch getting hot

Originally Posted by LAFireboyd
All you should work with is the fan switch's single green wire(ground wire)... no hot wires and no relays, as those are already connected. So if you're working with the hot wire, then, in effect, it's probably like having connected the power twice, thereby overloading the circuit.

Near the fan switch, splice a wire into the switch's single green wire; run the new wire into the car and connect it to one side of a two-prong toggle switch; wire the other prong to the metal dash frame... done. Flipping the switch completes the ground, turning on the fan.

It's that simple--really.

The hot wire coming off the fan goes to the toggle switch which receives its power from a wire coming from the fuse box to the toggle switch, its not getting power twice.
Old 03-12-2010, 09:41 AM
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Car: LOWERED ♦ CRIMSON METALFLAKE
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Transmission: 765R4
Axle/Gears: EATON POSI 4.56
Switch Fix

The hot wire coming off the fan goes to the toggle switch which receives its power from a wire coming from the fuse box to the toggle switch………
That’s why the switch is getting hot.

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Happy Racing!

If People Drove Any Slower They’d Be Going Backwards
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